chịu mình không thể giải được

Mấy con gà lắt nhắt này, dễ thế mà cũng ko tính đc.

Bạn ơi bạn làm đc bao nhiêu thì làm phụ mình nhé 

bài1

a, 

5 - 7 + 3 +(-8)

= -2 + 3 + ( - 8)

=     1    + (-8)= -7

-4/5 + 11/3 - 9/10       =(-4/5 + 11/3) -9/10              =43/15 -9/10        =59/30                                                                                                      5/6 + -7/15 - 13/30            =(5/6 + -7/15) -13/30                =11/30 - 13/30          =-1/15                                                                                                           CHÚC EM HỌC TỐT ^_^

a) 1-5+7-8+4-1+5-7+8

=(1-1) - (-5+5) -(7-7) -(-8+8) +4

=0

b)=-39+9

=-30

c)=(20-20)-(-4+4)-(8-8)-17+15

=-2

d)= (13-13)-(-98+98)-(91-91)-75

=-75

1. -x+20 = -(-15)-8+13

=> -x=15-8+13-20

=> -x=0

=> x=0

2. -(-10)+x=-13+(-9)+(-6)

=> 10+x=-13-9-6

=> x = -13-9-6-10

=> x = -38

3. 8-(-12)+10=-(-14)-x

=> 8+12+10=14-x

=> x = 14-8-12-10

=> x = -16

4. -(+12)+(-x)-(-3)=5-(-7)

=> -12-x+3=5+7

=> -x=5+7+12-3

=> -x=21

=> x=-21

5. 14-x+(-10)=-(-9)+(+15)

=> 14-x-10=9+15

=> -x=9+15-14+10

=> -x=20

=> x=-20

6. 12-(-17)+(-3)=-5+x

=> 12+17-3+5=x

=> x=31

7. x-(-19)-(+32)=14-(+16)

=> x+19-32=14-16

=> x=14-16+32-19

=> x=11

8. x-|-15|-|7|=-(-9)+|-5|

=> x-15-7=9+5

=> x=9+5+7+15

=> x=36

9. 15-x+17=13-(-21)

=> 15-x+17=13+21

=> -x=13+21-15-17

=> -x=2

=> x=-2

10. -|-5|-(-x)+4=3-(-25)

=> -5+x+4=3+25

=> x=3+25-4+5

=> x=29

\(\frac{1.3.5+2.6.10+4.12.20+7.21.35}{1.5.7+2.10.14+4.20.28+7.35.49}\)

\(=\frac{1.3.5\left(1+2+4+7\right)}{1.5.7\left(1+2+7+7\right)}=\frac{1.3.5}{1.5.7}=\frac{15}{35}=\frac{3}{7}\)

\(\frac{1\cdot3\cdot5+2\cdot6\cdot10+4\cdot12\cdot20+7\cdot21\cdot35}{1\cdot5\cdot7+2\cdot10\cdot14+4\cdot20\cdot28+7\cdot35\cdot49}\)

\(=\)\(\frac{1\cdot3\cdot5\cdot\left(1+2+4+7\right)}{1\cdot5\cdot7\cdot\left(1+2+7+7\right)}\)

\(=\frac{1\cdot3\cdot5}{1\cdot5\cdot7}\)\(=\frac{15}{35}=\frac{3}{7}\)

bn vội quá viết nhầm lun kìa 

hj hj chúc bn làm bài tốt nha

a, -(-5)-(+7)+(+3)+(-8)

= 5 - 7 + 3 + (-8)

= (-2) + 3 + (-8)

= 1 + (-8)

= -7

b, -(-15)-|-10|+|-9|-|5I

= 15 - 10 + 9 - 5

= 5 + 9 - 5

= 14 - 5

= 9

c, 14-(-13)-(17)+(-12)

= 14 + 13 - 17 + (-12)

= 27 - 17 + (-12)

= 10 + (-12)

= 2

d, -|-14| + |-10| - (-12) + (-8)

= -14 + 10 + 12 + (-8)

= (-4) + 12 + (-8)

= 7 + (-8)

= -1

e, -(-11) + (-15) + (13) - 21

toan lop 6 ma chi

a) \(\dfrac{-5}{11}+\left(\dfrac{-6}{11}+1\right)\)

\(=\dfrac{-5}{11}+\left(\dfrac{-6}{11}+\dfrac{11}{11}\right)\)

\(=\dfrac{-5}{11}+\dfrac{5}{11}\)

\(=0\)

b) \(\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\)

\(=\dfrac{2}{3}+\dfrac{-2}{3}+\dfrac{5}{7}\)

\(=0+\dfrac{5}{7}\)

\(=\dfrac{5}{7}\)

c) \(\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\)

\(=\dfrac{-1}{4}+\dfrac{-3}{8}+\dfrac{5}{8}\)

\(=\dfrac{-2}{8}+\dfrac{-3}{8}+\dfrac{5}{8}\)

\(=0\)

d) \(\dfrac{3}{4}.\dfrac{7}{25}+\dfrac{3}{4}.\dfrac{18}{25}\)

\(=\dfrac{3}{4}.\left(\dfrac{7}{25}+\dfrac{18}{25}\right)\)

\(=\dfrac{3}{4}.1\)

\(=\dfrac{3}{4}\)

Chúc bạn học tốt

KHO THE

\(A=\frac{\left[\left(25-1\right):1+1\right]\left(25+1\right)}{2}=325.\)

\(B=\frac{\left[\left(51-3\right):2+1\right]\left(51+3\right)}{2}=675\)

\(C=\frac{\left[\left(81-1\right):4+1\right]\left(81+1\right)}{2}=861\)